Vue compiler adds import of mergeModels from vue, while it is not exposed in typings. about core

[LinusBorg]

This is an issue with the rollup setup is essentially typechecking the generated code after template compilation - that code is not meant to be typechecked.

The mergeModels helper function is explicitly marked as internal because it's only used/inserted by the compiler and not considered a public API - so we don't want it to be exposed in vue's type declarations.

We 'strongly recommend using vue-tsc to generate type declarations instead:

https://vuejs.org/guide/typescript/overview.html#overview

If using SFCs, use the vue-tsc utility for command line type checking and type declaration generation. vue-tsc is a wrapper around tsc, TypeScript's own command line interface. It works largely the same as tsc except that it supports Vue SFCs in addition to TypeScript files. You can run vue-tsc in watch mode in parallel to the Vite dev server, or use a Vite plugin like vite-plugin-checker which runs the checks in a separate worker thread.

[yyx990803]

This is a wontfix. Like @LinusBorg said, type checking should only happen to user-authored source code, not transformed / generated code.

[SimmeNilsson]

Thank you both for the explanation.
If vue-tsc is the recommended path to generate the typings, what is the preferred way to generate the js-part for SFCs in a library?
Being able to do both in one step was the reason we went with rollup instead of vue-tsc in the first place.

[yyx990803]

Use Vite (which is using Rollup under the hood) + @vitejs/plugin-vue

If you have to stick to plain Rollup for some reason, you can use a Rollup plugin that only performs TS transpilation without type checking, e.g. https://www.npmjs.com/package/rollup-plugin-esbuild

[SimmeNilsson]

Thank you! We've switched now. 👍